Evaluation of the strength and creep-fatigue behavior of hot isostatically pressed silicon nitride
- High Temperature Materials Lab., Oak Ridge National Lab., Oak Ridge, TN (United States)
This paper reports that the strength of a commerically available hot isostatically pressed silicon nitride was measured as a function of temperature. To evaluate long-term mechanical reliability of this material, the tensile creep and fatigue behavior was measured at 1150[degrees], 1260[degrees], and 1370[degrees]C. The stress and temperature sensitivities of the secondary (or minimum) creep strain rate were used to estimate the stress exponent and activation energy associated with the dominant creep mechanism. The fatigue characteristics were evaluated by allowing individual creep tests to continue until specimen failure. The applicability of the four-point load geometry to the study of strength and creep behavior was also determined by conducting a limited number of flexural creep tests. The tensile fatigue data revealed two distinct failure mechanisms. At 1150[degrees]C, failure was controlled by a slow crack growth mechanism. At 1260[degrees] and 1370[degrees]C, the accumulation of creep damage in the form of grain boundary cavities and cracks dominated the fatigue behavior. In this temperature regime, the fatigue life was controlled by the secondary (or minimum) creep strain rate in accordance with the Monkman-Grant relation.
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6987023
- Journal Information:
- Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 75:9; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
Similar Records
Creep and slow crack growth mechanisms related to macroscopic creep behaviour of a silicon nitride ceramic at elevated temperatures
Creep and slow crack growth mechanisms related to macroscopic creep behaviour of a silicon nitride ceramic at elevated temperatures
Related Subjects
360101 -- Metals & Alloys-- Preparation & Fabrication
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
360104 -- Metals & Alloys-- Physical Properties
ACTIVATION ENERGY
CREEP
CRYSTAL STRUCTURE
ENERGY
EVALUATION
FABRICATION
FATIGUE
FLEXURAL STRENGTH
FRACTURE MECHANICS
GRAIN BOUNDARIES
HEAT TREATMENTS
HOT PRESSING
MATERIALS WORKING
MECHANICAL PROPERTIES
MECHANICS
MICROSTRUCTURE
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
PRESSING
RELIABILITY
SILICON COMPOUNDS
SILICON NITRIDES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 1000-4000 K
THERMOMECHANICAL TREATMENTS